Monitoring systems such as heating, ventilating and air conditioning (HVAC) systems for a property often include one or more light-emitting diode (LED) indicators that provide a system status. For example, LED indicators can use blink patterns to indicate various problems related to the operation of the system. A service technician can use a blink pattern to manually diagnose a system fault based on observing a sequence of the blink pattern, or based on lights turning on and off.